'e-Nose' breath test detects TB

Researchers from the Netherlands and Bangladesh have developed a device to detect tuberculosis, which they hope will revolutionise the diagnostic process, especially in poorer countries.

They hope the 'electronic nose', or eNose, will replace conventional diagnostic methods used currently, which involve taking cultures in a laboratory from a patient's sputum, as well as lung X-rays.

It can take weeks or months to develop a sputum cultures in a laboratory, and doctors get no clues from the technique about the type of infection present, particularly whether it is a drug-resistant form.

By contrast, the new test can detect volatile compounds in exhaled air from a patient that are produced by the bacteria that cause TB, mycobacterium tuberculosis.

According to a seven-month pilot study carried out in partnership with Bangladesh's National TB Control Programme, the e-Nose is straightforward to use, fast, highly sensitive and specific.

The study, which was published in Tuberculosis Journal, involved around 230 subjects, some of whom were healthy and some of whom had active TB.

Lead researcher Zeaur Rahim, of the International Centre for Diarrhoeal Disease Research, the e-Nose device will give significant advantage to users in places with a high TB infection burden like Bangladesh.

The diagnostic process was risk-free to healthcare workers, because no contact with patients' biological samples was required, he said.

In countries which have a high prevalence of pulmonary TB, accurate and early diagnosis is crucial to controlling the disease.

A new TB infection occurs somewhere in the world every second, with 1.5 million TB-related deaths annually, according to the World Health Organisation (WHO).

A recent WHO report said there were still 8.8 million new TB infections every year.

The e-Nose device has metal oxide sensors that detect volatile organic compounds in a sample of exhaled air from a patient, who simply blows into an airbag for the test.

Computers can analyse the results from the sensors, and compare them with results for normal air. The device can often pick up traces of bacteria other that M. tuberculosis.

If healthcare providers use the commercially available version of the tool, DiagNose, the cost of each TB test could be reduced to as little as US$10 per test, far less than the cost of currently available diagnostic tests.

According to Marcel Bruins, a Dutch researcher with the eNose company, the company aimed to market a user-friendly, low-cost TB-screening device for use anywhere in the world.

The software could be adjusted for use in different parts of the world, because TB strains may vary greatly from place to place, he said.